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Keywords = low cation mixing

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16 pages, 3885 KiB  
Article
Synthesis and Properties of Bi1.8Mn0.5Ni0.5Ta2O9-Δ Pyrochlore
by Sergey V. Nekipelov, Olga V. Petrova, Alexandra V. Koroleva, Mariya G. Krzhizhanovskaya, Kristina N. Parshukova, Nikolay A. Sekushin, Boris A. Makeev and Nadezhda A. Zhuk
Chemistry 2025, 7(4), 119; https://doi.org/10.3390/chemistry7040119 - 25 Jul 2025
Viewed by 172
Abstract
Pyrochlore Bi1.8Mn0.5Ni0.5Ta2O9-Δ (sp.gr. Fd-3m, a = 10.5038(9) Å) was synthesized by the solid-phase reaction method and characterized by vibrational and X-ray spectroscopy. According to scanning electron microscopy, the ceramics are characterized by a [...] Read more.
Pyrochlore Bi1.8Mn0.5Ni0.5Ta2O9-Δ (sp.gr. Fd-3m, a = 10.5038(9) Å) was synthesized by the solid-phase reaction method and characterized by vibrational and X-ray spectroscopy. According to scanning electron microscopy, the ceramics are characterized by a porous microstructure formed by randomly oriented oblong grains. The average crystallite size determined by X-ray diffraction is 65 nm. The charge state of transition element cations in the pyrochlore was analyzed by soft X-ray spectroscopy using synchrotron radiation. For mixed pyrochlore, a characteristic shift of Bi4f and Ta4f and Ta5p spectra to the region of lower energies by 0.25 and 0.90 eV is observed compared to the binding energy in Bi2O3 and Ta2O5 oxides. XPS Mn2p spectrum of pyrochlore has an intermediate energy position compared to the binding energy in MnO and Mn2O3, which indicates a mixed charge state of manganese (II, III) cations. Judging by the nature of the Ni2p spectrum of the complex oxide, nickel ions are in the charge state of +(2+ζ). The relative permittivity of the sample in a wide temperature (up to 350 °C) and frequency range (25–106 Hz) does not depend on the frequency and exhibits a constant low value of 25. The minimum value of 4 × 10−3 dielectric loss tangent is exhibited by the sample at a frequency of 106 Hz. The activation energy of conductivity is 0.7 eV. The electrical behavior of the sample is modeled by an equivalent circuit containing a Warburg diffusion element. Full article
(This article belongs to the Section Inorganic and Solid State Chemistry)
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17 pages, 2732 KiB  
Article
Influence of Cellulose Nanocrystals and Surfactants on Catastrophic Phase Inversion and Stability of Emulsions
by Daniel Kim and Rajinder Pal
Colloids Interfaces 2025, 9(4), 46; https://doi.org/10.3390/colloids9040046 - 11 Jul 2025
Viewed by 248
Abstract
This study presents the first quantitative comparison of catastrophic phase inversion behavior of water-in-oil emulsions stabilized by nanocrystalline cellulose (NCC) and molecular surfactants with different headgroup charge types: anionic (sodium dodecyl sulfate referred to as SDS), cationic (octadecyltrimethylammonium chloride referred to as OTAC), [...] Read more.
This study presents the first quantitative comparison of catastrophic phase inversion behavior of water-in-oil emulsions stabilized by nanocrystalline cellulose (NCC) and molecular surfactants with different headgroup charge types: anionic (sodium dodecyl sulfate referred to as SDS), cationic (octadecyltrimethylammonium chloride referred to as OTAC), nonionic (C12–14 alcohol ethoxylate referred to as Alfonic), and zwitterionic (cetyl betaine referred to as Amphosol). By using conductivity measurements under controlled mixing and pendant drop tensiometry, this study shows that NCC markedly delays catastrophic phase inversion through interfacial jamming, whereas surfactant-stabilized systems exhibit concentration-dependent inversion driven by interfacial saturation. Specifically, NCC-stabilized emulsions exhibited a nonlinear increase in the critical aqueous phase volume fraction required for inversion, ranging from 0.253 (0 wt% NCC) to 0.545 (1.5 wt% NCC), consistent with enhanced resistance to inversion typically associated with the formation of rigid interfacial layers in Pickering emulsions. In contrast, surfactant-stabilized systems exhibited a concentration-dependent inversion trend with opposing effects. At low concentrations, limited interfacial coverage delayed inversion, while at higher concentrations, increased surfactant availability and interfacial saturation promoted earlier inversion and favored the formation of oil-in-water structures. Pendant drop tensiometry confirmed negligible surface activity for NCC, while all surfactants significantly lowered interfacial tension. Despite its weak surface activity, NCC imparted strong coalescence resistance above 0.2 wt%, attributed to steric stabilization. These findings establish distinct mechanisms for governing phase inversion in particle- versus surfactant-stabilized systems. To our knowledge, this is the first study to quantitively characterize the catastrophic phase inversion behavior of water-in-oil emulsions using NCC. This work supports the use of NCC as an effective stabilizer for emulsions with high internal phase volume. Full article
(This article belongs to the Special Issue Rheology of Complex Fluids and Interfaces: 2nd Edition)
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19 pages, 15843 KiB  
Article
Hydrochemical Characteristics and Formation Mechanisms of Groundwater in the Nanmiao Emergency Groundwater Source Area, Yichun, Western Jiangxi, China
by Shengpin Yu, Tianye Wang, Ximin Bai, Gongxin Chen, Pingqiang Wan, Shifeng Chen, Qianqian Chen, Haohui Wan and Fei Deng
Water 2025, 17(14), 2063; https://doi.org/10.3390/w17142063 - 10 Jul 2025
Viewed by 288
Abstract
The Nanmiao Emergency Groundwater Source Area, rich in H2SiO3, serves as a strategic freshwater reserve zone in western Jiangxi Province. However, the mechanisms underlying groundwater formation in this area remain unclear. This study applied a combination of statistical analysis, [...] Read more.
The Nanmiao Emergency Groundwater Source Area, rich in H2SiO3, serves as a strategic freshwater reserve zone in western Jiangxi Province. However, the mechanisms underlying groundwater formation in this area remain unclear. This study applied a combination of statistical analysis, isotopic tracing, and hydrochemical modeling to reveal the hydrochemical characteristics and origins of groundwater in the region. The results indicate that Na+ and Ca2+ dominate the cations, while HCO3 and Cl dominate the anions. Groundwater from descending springs is characterized by low mineralization and weak acidity, with hydrochemical types of primarily HCO3–Na·Mg and HCO3–Mg·Na·Ca. Groundwater from boreholes is weakly mineralized and neutral, with dominant hydrochemical types of HCO3–Ca·Na and HCO3–Ca·Na·Mg, suggesting a deep circulation hydrogeochemical process. Hydrogen and oxygen isotope analysis indicates that atmospheric precipitation is the primary recharge source. The chemical composition of groundwater is mainly controlled by rock weathering, silicate mineral dissolution, and cation exchange processes. During groundwater flowing, water and rock interactions, such as leaching, cation exchange, and mixing, occur. This study identifies the recharge sources and circulation mechanisms of regional groundwater, offering valuable insights for the sustainable development and protection of the emergency water source area. Full article
(This article belongs to the Special Issue Advances in Surface Water and Groundwater Simulation in River Basin)
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117 pages, 10736 KiB  
Review
Design Principles and Engineering Strategies for Stabilizing Ni-Rich Layered Oxides in Lithium-Ion Batteries
by Alain Mauger and Christian M. Julien
Batteries 2025, 11(7), 254; https://doi.org/10.3390/batteries11070254 - 4 Jul 2025
Viewed by 923
Abstract
Nickel-rich layered oxides such as LiNixMnyCozO2 (NMC), LiNixCoyAlzO2 (NCA), and LiNixMnyCozAl(1–xyz)O2 (NMCA), where x [...] Read more.
Nickel-rich layered oxides such as LiNixMnyCozO2 (NMC), LiNixCoyAlzO2 (NCA), and LiNixMnyCozAl(1–xyz)O2 (NMCA), where x ≥ 0.6, have emerged as key cathode materials in lithium-ion batteries due to their high operating voltage and superior energy density. These materials, characterized by low cobalt content, offer a promising path toward sustainable and cost-effective energy storage solutions. However, their electrochemical performance remains below theoretical expectations, primarily due to challenges related to structural instability, limited thermal safety, and suboptimal cycle life. Intensive research efforts have been devoted to addressing these issues, resulting in substantial performance improvements and enabling the development of next-generation lithium-ion batteries with higher nickel content and reduced cobalt dependency. In this review, we present recent advances in material design and engineering strategies to overcome the problems limiting their electrochemical performance (cation mixing, phase stability, oxygen release, microcracks during cycling). These strategies include synthesis methods to optimize the morphology (size of the particles, core–shell and gradient structures), surface modifications of the Ni-rich particles, and doping. A detailed comparison between these strategies and the synergetic effects of their combination is presented. We also highlight the synergistic role of compatible lithium salts and electrolytes in achieving state-of-the-art nickel-rich lithium-ion batteries. Full article
(This article belongs to the Special Issue Batteries: 10th Anniversary)
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16 pages, 1636 KiB  
Article
Lithological Controls on Chemical Weathering and CO2 Consumption at Small Watershed Scale: Insights from Hydrochemistry and Stable Carbon Isotope
by Yuanzheng Zhang, Wenlong Huang, Zhuohan Zhuang, Jing Hua, Litong Bai, Yi Ding, Ling Zheng, Cheng Wang, Chuang Zhao and Yunde Liu
Water 2025, 17(13), 2008; https://doi.org/10.3390/w17132008 - 4 Jul 2025
Viewed by 329
Abstract
Previous investigations into lithology-driven weathering processes have largely emphasized large-scale spatial assessments, while studies targeting small watershed scales remain scarce. This study investigated two adjacent watersheds (Chengjia: CJ; Datan: DT) under comparable climatic conditions in Guangdong, China, using hydrochemistry and stable carbon isotopes. [...] Read more.
Previous investigations into lithology-driven weathering processes have largely emphasized large-scale spatial assessments, while studies targeting small watershed scales remain scarce. This study investigated two adjacent watersheds (Chengjia: CJ; Datan: DT) under comparable climatic conditions in Guangdong, China, using hydrochemistry and stable carbon isotopes. The CJ watershed exhibited low-TDS (20–66 mg/L) HCO3-Na·Ca-type waters dominated by silicate weathering, whereas the DT watershed displayed high-TDS (70–278 mg/L) HCO3-Ca-type waters, indicative of mixed carbonate–silicate weathering. Results of carbon isotope composition of dissolved inorganic carbon confirmed that H2CO3-driven weathering was the dominant mechanism in both watersheds. In the CJ watershed, 79.5% of dissolved cations in surface water originated from silicate weathering, yielding a CO2 consumption rate (CCR) of 0.28 × 106 mol/km2/yr, while carbonate weathering was negligible. Conversely, in the DT watershed, 86.4% of dissolved cations were derived from carbonate weathering, yielding a CCR of 1.94 × 106 mol/km2/yr, whereas silicate weathering contributed only 10.3% of cations with a CCR of 0.23 × 106 mol/km2/yr. The chemical weathering rate of carbonate can be up to 10 times that of silicate, resulting in a larger CCR. This study demonstrated the key impact of lithology on hydrochemical characteristics and CO2 consumption at small watershed scales. Full article
(This article belongs to the Special Issue Water–Rock Interaction)
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18 pages, 4005 KiB  
Article
Measurement and Modelling of Carbon Dioxide in Triflate-Based Ionic Liquids: Imidazolium, Pyridinium, and Pyrrolidinium
by Raheem Akinosho, Amr Henni and Farhan Shaikh
Liquids 2025, 5(2), 15; https://doi.org/10.3390/liquids5020015 - 30 May 2025
Viewed by 406
Abstract
Carbon dioxide, the primary greenhouse gas responsible for global warming, represents today a critical environmental challenge for humans. Mitigating CO2 emissions and other greenhouse gases is a pressing global concern. The primary goal of this study is to investigate the potential of [...] Read more.
Carbon dioxide, the primary greenhouse gas responsible for global warming, represents today a critical environmental challenge for humans. Mitigating CO2 emissions and other greenhouse gases is a pressing global concern. The primary goal of this study is to investigate the potential of particular ionic liquids (ILs) in capturing CO2 for the sweetening of natural and other gases. The solubility of CO2 was measured in three distinct ILs, which shared a common anion (triflate, TfO) but differed in their cations. The selected ionic liquids were {1-butyl-3-methylimidazolium triflate [BMIM][TfO], 1-butyl-1-methylpyrrolidinium triflate [BMP][TfO], and 1-butyl-4-methylpyridium triflate [MBPY][TfO]}. The solvents were screened based on results from a molecular computational study that predicted low CO2 Henry’s Law constants. Solubility measurements were conducted at 303.15 K, 323.15 K, and 343.15 K and pressures up to 1.5 MPa using a gravimetric microbalance (IGA-003). The CO2 experimental results were modeled using the Peng–Robinson Equation of state with three mixing rules: van der Waals one (vdWI), van der Waals two (vdWII), and the non-random two-liquid (NRTL) Wong–Sandler (WS) mixing rule. For the three ILs, the NRTL-WS mixing rule regressed the data with the lowest average deviation percentage of 1.24%. The three solvents had similar alkyl chains but slightly different polarities. [MBPY][TfO], with the largest size, exhibited the highest CO2 solubility at all three temperatures. Calculation of its relative polarity descriptor (N) shows it was the least polar of the three ILs. Conversely, [BMP][TfO] showed the highest Henry’s Law constant (lowest solubility) across the studied temperature range. Comparing the results to published data, the study concludes that triflate-based ionic liquids with three fluorine atoms had lower capacity for CO2 compared to bis(trifluoromethylsulfonyl) imide (Tf2N)-based ionic liquids with six fluorine atoms. Additionally, the study provided data on the enthalpy and entropy of absorption. A final comparison shows that the ILs had a lower CO2 capacity than Selexol, a solvent widely used in commercial carbon capture operations. Compared to other ILs, the results confirm that the type of anion had a more significant impact on solubility than the cation. Full article
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21 pages, 2052 KiB  
Article
Optimizing Oilfield-Produced Water Reuse for Sustainable Irrigation: Impacts on Soil Quality and Mineral Accumulation in Plants
by Khaled Al-Jabri, Ahmed Al-Busaidi, Mushtaque Ahmed, Rhonda R. Janke and Alexandros Stefanakis
Water 2025, 17(10), 1497; https://doi.org/10.3390/w17101497 - 16 May 2025
Viewed by 1854
Abstract
The effective management of produced water (PW), a by-product of oil extraction in Oman, is essential for sustainable water use and environmental protection. PW contains petroleum residues, heavy metals, and salts, which require treatment before safe reuse. In the Nimr oil field, PW [...] Read more.
The effective management of produced water (PW), a by-product of oil extraction in Oman, is essential for sustainable water use and environmental protection. PW contains petroleum residues, heavy metals, and salts, which require treatment before safe reuse. In the Nimr oil field, PW undergoes partial treatment in constructed wetlands vegetated with buffelgrass (Cenchrus ciliaris). This study investigated the reuse potential of treated PW for irrigation through two parallel field experiments conducted at Sultan Qaboos University (SQU) and the Nimr wetlands site. At the SQU site, native halophytic plants were irrigated with three water sources: treated municipal wastewater, underground water (from an on-site well), and treated produced water. At the Nimr site, irrigation was conducted using underground water and treated PW. Two soil types were used: well-draining control soil and Nimr soil from southern Oman. The treatments included: (i) PW + control soil, (ii) PW + Nimr soil, (iii) PW + gypsum (3.5 g/kg soil), (iv) PW + biochar (10 g/kg soil), (v) underground water + control soil, and (vi) treated municipal wastewater + control soil. Biochar, produced from locally sourced buffelgrass via low-temperature pyrolysis (300 °C for 3 h), and gypsum (46.57% acid-extractable sulfate) were mixed into the soil before sowing. The impact of each treatment was assessed in terms of soil quality (salinity, boron, major cations), plant physiological responses, and mineral accumulation. PW irrigation (TDS ~ 6500–7000 mg/L) led to a sixfold increase in soil sodium and raised boron levels in plant tissues to over 200 mg/kg, exceeding livestock feed safety limits. Copper remained within acceptable thresholds (≤9.5 mg/kg). Biochar reduced boron uptake, but gypsum showed limited benefit. Neither amendment improved plant growth under PW irrigation. These findings highlight the need for regulated PW reuse, emphasizing the importance of soil management strategies and alternating water sources to mitigate salinity stress. Full article
(This article belongs to the Special Issue Effects of Hydrology on Soil Erosion and Soil Water Conservation)
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14 pages, 4247 KiB  
Article
Zn-Based Three-Dimensional Metal-Organic Framework for Selective Fluorescence Detection in Zwitterionic Ions
by Hongbin Liu, Yue Zhao, Biyi Huang, Hui Liu, Putao Zhang, Wen Gu and Tingli Ma
Int. J. Mol. Sci. 2025, 26(8), 3566; https://doi.org/10.3390/ijms26083566 - 10 Apr 2025
Viewed by 486
Abstract
Zinc-based MOFs exhibit significant advantages in ion detection due to their unique structure and chemical properties. They can efficiently and selectively recognize and detect specific ions, making them powerful analytical tools for applications in environmental monitoring, biomedical fields, and more. In this work, [...] Read more.
Zinc-based MOFs exhibit significant advantages in ion detection due to their unique structure and chemical properties. They can efficiently and selectively recognize and detect specific ions, making them powerful analytical tools for applications in environmental monitoring, biomedical fields, and more. In this work, we used a simple ligand to improve the coordination environment of Zn2+ ions and successfully synthesized a 3D coordination compound Zn(all-bdc)(Py) MOF through a straightforward hydrothermal method at low temperature. Additionally, we explored the potential of this MOF as a bifunctional ion fluorescence probe for both cationic and anionic recognition. The results showed that this 3D porous MOF exhibited excellent recognition ability for trivalent iron ions (Fe3+) and potassium permanganate (KMnO4) ions due to its highly porous structures and efficient ion recognition. When iron ions were added to 500 μL and potassium permanganate ions were added to 100 μL, the fluorescence of the compound was effectively quenched, and the detection limits for these two ions were 0.95 μM and 0.13 μM, respectively. The mixed-ion experiments also demonstrated that even in the presence of similar ions, this 3D MOF still maintained good selective recognition ability, specifically identifying Fe3+ and KMnO4 ions. This work provides a novel synthetic strategy for the design of MOFs capable of mixed-ion recognition and detection, expanding their application potential in ion sensing and analysis. Full article
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16 pages, 2720 KiB  
Article
Ultrapure Water Production by a Saline Industrial Effluent Treatment
by Adriana Hernández Miraflores, Karina Hernández Gómez, Claudia Muro, María Claudia Delgado Hernández, Vianney Díaz Blancas, Jesús Álvarez Sánchez and German Eduardo Devora Isordia
Membranes 2025, 15(4), 116; https://doi.org/10.3390/membranes15040116 - 7 Apr 2025
Cited by 1 | Viewed by 872
Abstract
A membrane system was applied for ultrapure water production from the treatment of saline effluent from the canned food industry. The industrial effluent presented a high saline concentration, including sodium chloride, calcium carbonate, calcium sulfates, and magnesium. The effluent was treated using a [...] Read more.
A membrane system was applied for ultrapure water production from the treatment of saline effluent from the canned food industry. The industrial effluent presented a high saline concentration, including sodium chloride, calcium carbonate, calcium sulfates, and magnesium. The effluent was treated using a system of reverse osmosis (RO) and a post-treatment process consisting of ion exchange resins (IEXRs). The RO was accompanied by the addition of a hexametaphosphate dose (2, 6, and 10 mg/L) as an antiscalant to avoid the RO membrane scaling by minerals. In turn, IEXRs were used for water deionization to produce ultrapure water with a reduced concentration of monovalent ions. The antiscalant dose was 6 mg/L, producing clean water from RO permeates with an efficiency of 65–70%. The brine from RO was projected for its reuse in food industry processes. The clean water quality from RO showed 20% total dissolved solids (TDS) removal (equivalent to salts). The antiscalant inhibited the formation of calcium salt incrustation > 200 mg/L, showing low fouling. In turn, anionic resins removed 99.8% of chloride ions, whereas the monovalent salts were removed by a mix of cationic–anionic resin, producing ultrapure water with electrical conductivity < 3.3 µS/cm. The cost of ultrapure water production was 2.62 USD/m3. Full article
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22 pages, 4834 KiB  
Article
Synthesis and Evaluation of a Chitosan-Based Cationic Hydrogel with Strong Antifungal and Antibiofilm Activities Against Clinical Isolates of Candida auris
by Muhammad Kamran, Maryam Aftab, Afreenish Amir, Fatima Javed, Amtul Quddos Latif, Kausar Abbas Saldera, Abdul Ahad, Yousef A. Bin Jardan, Louise Ann Walker, Kiran Nisa, Faheem Ullah and Naseer Ali Shah
Pharmaceuticals 2025, 18(4), 506; https://doi.org/10.3390/ph18040506 - 31 Mar 2025
Viewed by 1091
Abstract
Background: Candida auris is a significant global health concern, due to its rapid transmission, high mortality rate, and resistance to commonly available antifungal drugs. Methodology: During the current study, a cationic polymeric hydrogel was developed using chitosan (CS), polyethylene glycol (PEG), and methacrylic [...] Read more.
Background: Candida auris is a significant global health concern, due to its rapid transmission, high mortality rate, and resistance to commonly available antifungal drugs. Methodology: During the current study, a cationic polymeric hydrogel was developed using chitosan (CS), polyethylene glycol (PEG), and methacrylic acid (MAA). The respective solutions were mixed in a volumetric ratio of 2:1:1. After characterization, the hydrogel was assessed using antifungal, antibiofilm, and hemocompatibility assays. Results: The hydrodynamic radius of 554.7 ± 90.1 nm and zeta potential of 15.6 ± 1.09 mV indicate the ideal size and charge for topical applications and in vivo studies, respectively. The formulation exhibited improved thermal stability, enhanced swelling, and a drug release profile for non-Fickian diffusion. The hydrogel effectively inhibited fungal growth in agar plates (42 ± 7.31 mm zone of inhibition), with a mean IC50 of 15.17 ± 4.01 μg/mL and MIC of 29.30 ± 11.72 μg/mL. Calcofluor white (CFW) staining showed diffuse irregular yeast cells, suggesting increased membrane permeability, eventually leading to cell death. The hemocompatibility assay revealed no visible agglutination or hemolysis at the MIC value. The formulation exhibited significantly reduced biofilm formation compared to the growth control (p < 0.05). Additionally, in silico analysis revealed that MAA showed superior oral bioavailability, no inhibitory activity on cytochrome P450 enzymes, and low potential for toxicity through nuclear receptor signaling pathways. Conclusions: Cationic hydrogels show promise as potential antifungal treatments. The development of cost-effective and improved therapeutic methods is crucial to combat this deadly pathogen and to improve patient outcomes. Full article
(This article belongs to the Section Pharmaceutical Technology)
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15 pages, 6484 KiB  
Article
Multivariate Statistics and Hydrochemistry Combined to Reveal the Factors Affecting Shallow Groundwater Evolution in a Typical Area of the Huaibei Plain, China
by Xi Qin, Hesheng Wang, Jianshi Gong, Yonghong Ye, Kaie Zhou, Naizheng Xu, Liang Li and Jie Li
Water 2025, 17(7), 962; https://doi.org/10.3390/w17070962 - 26 Mar 2025
Viewed by 398
Abstract
Understanding the characteristics of groundwater chemistry is essential for water resource development and utilization. However, few studies have focused on the chemical evolution processes of shallow groundwater in typical areas of the Huaibei Plain. We analyzed 28 water samples from the study area [...] Read more.
Understanding the characteristics of groundwater chemistry is essential for water resource development and utilization. However, few studies have focused on the chemical evolution processes of shallow groundwater in typical areas of the Huaibei Plain. We analyzed 28 water samples from the study area using hydrogeochemical mapping, multivariate statistical analysis, and other approaches. The study found that the hydrogeochemical facies of groundwater are mainly HCO3-Ca·Mg (64.3%), mixed SO4·Cl-Ca·Mg, and SO4·Cl-Na. The hydrochemical composition is primarily controlled by natural water–rock interactions, including carbonate weathering and cation exchange processes. Correlation analysis and principal component analysis (PCA) revealed that mineral dissolution was the predominant source of Na+, Mg2+, Cl, and SO42− in shallow groundwater, significantly contributing to total dissolved solids (TDS) accumulation. Hierarchical cluster analysis (HCA) identified three characteristic zones: (1) agricultural/urban-influenced areas, (2) high-F/low-hardness zones, and (3) nitrate-contaminated regions. These findings provide critical insights for assessing the geochemical status of groundwater in the Huaibei Plain and formulating targeted resource management strategies. Full article
(This article belongs to the Special Issue Assessment of Groundwater Quality and Pollution Remediation)
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38 pages, 12618 KiB  
Article
Comparative Assessment of Chemical and Isotopic Composition of Geothermal Fluids in the Eastern Part of the Büyük Menderes Graben (Western Türkiye)
by Ali Gökgöz, Halim Mutlu and Erdem Subay
Water 2025, 17(7), 961; https://doi.org/10.3390/w17070961 - 25 Mar 2025
Viewed by 743
Abstract
In this study, we comparatively discuss chemical and isotopic characteristics of thermal waters from several geothermal fields within the eastern part of the Büyük Menderes graben, Western Türkiye. The studied thermal waters with a wide range of temperature (33 to 242 °C) and [...] Read more.
In this study, we comparatively discuss chemical and isotopic characteristics of thermal waters from several geothermal fields within the eastern part of the Büyük Menderes graben, Western Türkiye. The studied thermal waters with a wide range of temperature (33 to 242 °C) and pH value (6.10 to 9.38) show water types varying from Ca-Mg-HCO3-SO4 to Na-HCO3-SO4. The chemical composition of waters is controlled by several processes, which include temperature, circulation depth, extent of water–rock interaction, dissolution/precipitation, mixing, cation exchange and microbial activity. All thermal waters are of meteoric origin and generally have deep circulation. δ13C data indicate that marine limestone and mantle-derived CO2 are the major sources of carbon in thermal waters and δ34S values imply that the sulfate is originated from the Neogene gypsums. At discharge temperatures, all thermal waters are saturated with various carbonate, silica and clay minerals, which is supported by the XRD analysis of scaling materials. The REY composition of the scaling samples showed that the limestone is the source rock for the rare earth elements. Thermal waters with a positive 18O shift of 2.7 to 4.6‰ have reservoir temperatures of 170–245 °C, whilst other waters with a shift of <1‰ have reservoir temperatures in the range of 79 to 166 °C. Regarding the distribution of temperature, electricity production seems to be more suitable in the western part of the region, although relatively low-temperature areas in the east also look promising. Full article
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14 pages, 6183 KiB  
Article
Strontium Doping Promotes Low-Temperature Growth of Single-Crystalline Ni-Rich Cathodes with Enhanced Electrochemical Performance
by Jiaqi Wang, Yunchang Wang, Mengran Zheng and Feipeng Cai
Materials 2025, 18(6), 1320; https://doi.org/10.3390/ma18061320 - 17 Mar 2025
Cited by 1 | Viewed by 766
Abstract
Nickel-rich cathode materials have emerged as ideal candidates for electric vehicles due to their high energy density; however, polycrystalline materials are prone to microcrack formation and unavoidable side reactions with electrolytes during cycling, leading to structural instability and capacity degradation. Herein, an Sr-doped [...] Read more.
Nickel-rich cathode materials have emerged as ideal candidates for electric vehicles due to their high energy density; however, polycrystalline materials are prone to microcrack formation and unavoidable side reactions with electrolytes during cycling, leading to structural instability and capacity degradation. Herein, an Sr-doped single-crystalline nickel-rich LiNi0.88Co0.05Mn0.07O2/Sr cathode material is synthesized, with Sr doping levels controlled at x = 0.3%, 0.5%, 1 mol%. The nickel-rich LiNi0.88Co0.05Mn0.07O2/Sr cathode features particle sizes of approximately 2 μm, at a relatively low temperature. It inhibits the microcrack formation, prevents electrolyte penetration into the particle interior, and reduce side reactions, thereby enhancing structural stability. This enables the cathode to deliver a high initial discharge capacity of 205.3 mAh g−1at 0.1 C and 170.8 mAh g−1 at 10 C, within the voltage range of 2.7 V–4.3 V, and an outstanding capacity retention of 96.61% at 1 C after 100 cycles. These improvements can be attributed to the Sr-doping, which reduces the single-crystal growth temperature, effectively mitigating Li+/Ni2+ cation mixing. Moreover, the incorporation of Sr expands the interlayer spacing, thereby facilitating Li+ diffusion. The doping strategy employed in this work provides a new insight for low-temperature single-crystal materials synthesis, significantly improving the electrochemical performance of nickel-rich cathode materials. Full article
(This article belongs to the Section Energy Materials)
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18 pages, 6176 KiB  
Article
A Density Functional Valence Bond Study on the Excited States
by Xun Wu, Peikun Zheng, Tingzhen Chen, Chen Zhou, Peifeng Su and Wei Wu
Molecules 2025, 30(3), 489; https://doi.org/10.3390/molecules30030489 - 22 Jan 2025
Cited by 1 | Viewed by 1243
Abstract
The accurate description of excited states is crucial for the development of electronic structure theory. In addition to determining excitation energies, strong state interactions arise when electronic states with the same symmetry are degenerate or nearly degenerate, often requiring a multi-state treatment. These [...] Read more.
The accurate description of excited states is crucial for the development of electronic structure theory. In addition to determining excitation energies, strong state interactions arise when electronic states with the same symmetry are degenerate or nearly degenerate, often requiring a multi-state treatment. These strong correlation effects and state interactions can be effectively handled by the Hamiltonian matrix correction-based density functional valence bond (hc-DFVB) method, a multi-reference density functional theory capable of accurately describing electronic state interactions. In this paper, we explore the low-lying excited states of four isoelectronic systems (C2H, CN, CO+, BO) using valence bond methods, including the valence bond self-consistent field (VBSCF) and hc-DFVB methods. Our results show that the hc-DFVB method provides significantly better excitation energies compared to VBSCF. Furthermore, hc-DFVB can reliably predict the correct ordering of excited states, whereas VBSCF shows some ordering inconsistencies. By categorizing the VB structures into groups based on point group symmetry, we can extract the key structural contributions and bonding pictures of each state from the weight distribution of these groups. Additionally, we study the potential energy curves for lithium fluoride (LiF) and a mixed-valence spiro cation, demonstrating the superior performance of hc-DFVB when applied to the study of near-degenerate excited states in the avoided crossing region. Full article
(This article belongs to the Section Computational and Theoretical Chemistry)
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17 pages, 7586 KiB  
Article
Corrosion of Low-Alloy Steel in Ethanolamine Steam Generator Chemistry—The Effect of Temperature and Flow Rate
by Iva Betova, Martin Bojinov and Vasil Karastoyanov
Molecules 2025, 30(2), 418; https://doi.org/10.3390/molecules30020418 - 20 Jan 2025
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Abstract
The corrosion of low-alloy steel in ethanolamine solution, simulating steam generator chemistry, is studied by in situ chronopotentiometry and electrochemical impedance spectroscopy combined with ex situ analysis of the obtained oxide films and model calculations. Hydrodynamic calculations of the proposed setup to study [...] Read more.
The corrosion of low-alloy steel in ethanolamine solution, simulating steam generator chemistry, is studied by in situ chronopotentiometry and electrochemical impedance spectroscopy combined with ex situ analysis of the obtained oxide films and model calculations. Hydrodynamic calculations of the proposed setup to study flow-assisted corrosion demonstrate that turbulent conditions are achieved. Quantum chemical calculations indicate the adsorption orientation of ethanolamine on the oxide surface. Interpretation of impedance spectra with a kinetic approach based on the mixed-conduction model enabled estimating the rate constants of oxidation at the alloy–oxide interface, as well as charge transfer and ionic transport resistances of the corrosion process. In turbulent conditions, the dissolution of Fe oxide and ejection of Fe cations are enhanced, leading to Cr enrichment in the oxide and alteration of its electronic and electrochemical properties that influence the corrosion rate. Full article
(This article belongs to the Section Electrochemistry)
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